Motion Control proposes to develop an improved externally powered prosthetic hand/wrist system, which reduces the weight below the current standard, and integrated passive wrist flexion/extension into the hand. The need for such a hand/wrist system has been established in an extensive survey of arm amputees (Aitkins, et.al.,JPO, Vol 8/1, Winter 96). Arm amputees need flexion at the wrist to orient the hand to optimally grasp an object, or to reorient an object once it is grasped. The feasibility of this development has been supported by the accomplishments of Phase I. Objective number one was to develop a new prosthetic hand that is fully integrated with a passive wrist flexion/extension device. Objective number two was to reduce the weight of the hand. Both of these objectives have been met successfully and a preliminary prototype of this hand has been built and laboratory tested. During Phase II, we propose to complete three major design and testing iterations. The first iteration includes thorough laboratory testing; the next two iterations will be clinically tested. We are confident that this Phase II effort will lead to significant improvements to prosthetic hands for arm amputees, and will be a commercially viable product. PROPOSED COMMERCIAL APPLICATION: The expected results of this research will be a prosthetic hand/wrist system for upper extremity amputees. This hand and wrist system will be a significant improvement over currently available systems.